Quantify initial stability report edge cases.

components/metrics/metrics_log.cc

Index: components/metrics/metrics_log.cc
diff --git a/components/metrics/metrics_log.cc b/components/metrics/metrics_log.cc
index 691a946f9e6796d0ecd7051eddcbf569d51cc4d6..33981eed25163ab2b28c5df18f6e93c120787d72 100644
--- a/components/metrics/metrics_log.cc
+++ b/components/metrics/metrics_log.cc
@@ -117,9 +117,9 @@ MetricsLog::~MetricsLog() {
 
 // static
 void MetricsLog::RegisterPrefs(PrefRegistrySimple* registry) {
-  registry->RegisterIntegerPref(prefs::kStabilityLaunchCount, 0);
   registry->RegisterIntegerPref(prefs::kStabilityCrashCount, 0);
   registry->RegisterIntegerPref(prefs::kStabilityIncompleteSessionEndCount, 0);
+  registry->RegisterIntegerPref(prefs::kStabilityLaunchCount, 0);
   registry->RegisterIntegerPref(prefs::kStabilityBreakpadRegistrationFail, 0);
   registry->RegisterIntegerPref(
       prefs::kStabilityBreakpadRegistrationSuccess, 0);
@@ -129,6 +129,9 @@ void MetricsLog::RegisterPrefs(PrefRegistrySimple* registry) {
                                std::string());
   registry->RegisterStringPref(prefs::kStabilitySavedSystemProfileHash,
                                std::string());
+  registry->RegisterIntegerPref(prefs::kStabilityDeferredCount, 0);
+  registry->RegisterIntegerPref(prefs::kStabilityDiscardCount, 0);
+  registry->RegisterIntegerPref(prefs::kStabilityVersionMismatchCount, 0);
 }
 
 // static
@@ -242,6 +245,31 @@ void MetricsLog::RecordStabilityMetrics(
     pref->SetInteger(prefs::kStabilityDebuggerNotPresent, 0);
     stability->set_debugger_not_present_count(debugger_not_present_count);
   }
+
+  // Note: only logging the following histograms for non-zero values.
+
+  int deferred_count = pref->GetInteger(prefs::kStabilityDeferredCount);
+  if (deferred_count) {
+    local_state_->SetInteger(prefs::kStabilityDeferredCount, 0);
+    UMA_HISTOGRAM_COUNTS_100("Stability.InitialStabilityLog.DeferredCount",

[Alexei Svitkine (slow), 2016/09/02 17:57:49]

If you want these to be logged in the initial stability log, they need to be
logged with the Stability flag. This flag makes it so such histograms are added
to the initial stability log (as it ignores all other histograms).

We have UMA_STABILITY_HISTOGRAM_ENUMERATION() macro, but don't have
UMA_STABILITY_HISTOGRAM_COUNTS_100(). Feel free to add one.

[manzagop (departed), 2016/09/02 21:00:05]

Oh, good to know! Done.

+                             deferred_count);
+  }
+
+  int discard_count = local_state_->GetInteger(prefs::kStabilityDiscardCount);
+  if (discard_count) {
+    local_state_->SetInteger(prefs::kStabilityDiscardCount, 0);
+    UMA_HISTOGRAM_COUNTS_100("Stability.InitialStabilityLog.DiscardCount",

[Alexei Svitkine (slow), 2016/09/02 17:57:49]

Will these always be logged just in the initial stability log? What guarantees
that? (i.e. I don't see a check for f (log_type() == INITIAL_STABILITY_LOG)).

[manzagop (departed), 2016/09/02 21:00:05]

No, they might be logged with any log. My thinking is if there is no initial
log, this enables faster reporting.

The discard count is special in that it's not cleared on upgrade, so a given
version's data will also include discards of past versions, but I think that's
better if we want an idea of how much is lost. If we cared, we could have a
second histogram that is version specific, and gets cleared on upgrade.

[Alexei Svitkine (slow), 2016/09/08 18:41:12]

Ah, I see - the InitialStabilityLog refers to "what" they're talking about, not
where they're logged.

+                             discard_count);
+  }
+
+  int version_mismatch_count =
+      local_state_->GetInteger(prefs::kStabilityVersionMismatchCount);
+  if (version_mismatch_count) {
+    local_state_->SetInteger(prefs::kStabilityVersionMismatchCount, 0);
+    UMA_HISTOGRAM_COUNTS_100(
+        "Stability.InitialStabilityLog.VersionMismatchCount",
+        version_mismatch_count);
+  }
 }
 
 void MetricsLog::RecordGeneralMetrics(
@@ -401,7 +429,10 @@ void MetricsLog::RecordEnvironment(
   }
 }
 
-bool MetricsLog::LoadSavedEnvironmentFromPrefs() {
+bool MetricsLog::LoadSavedEnvironmentFromPrefs(std::string* app_version) {
+  DCHECK(app_version);
+  app_version->clear();
+
   PrefService* local_state = local_state_;
   const std::string base64_system_profile =
       local_state->GetString(prefs::kStabilitySavedSystemProfile);
@@ -415,10 +446,14 @@ bool MetricsLog::LoadSavedEnvironmentFromPrefs() {
 
   SystemProfileProto* system_profile = uma_proto()->mutable_system_profile();
   std::string serialized_system_profile;
-  return base::Base64Decode(base64_system_profile,
-                            &serialized_system_profile) &&
-         ComputeSHA1(serialized_system_profile) == system_profile_hash &&
-         system_profile->ParseFromString(serialized_system_profile);
+
+  bool success =
+      base::Base64Decode(base64_system_profile, &serialized_system_profile) &&
+      ComputeSHA1(serialized_system_profile) == system_profile_hash &&
+      system_profile->ParseFromString(serialized_system_profile);
+  if (success)
+    *app_version = system_profile->app_version();
+  return success;
 }
 
 void MetricsLog::CloseLog() {